var websocket = null;

var host = document.location.host;

var webSocketConnection = function () {
//判断当前浏览器是否支持WebSocket
    if ('WebSocket' in window) {
        // alert("浏览器支持Websocket")
        websocket = new WebSocket('ws://'+host+'/editor/webSocket/'+random_num);
    } else {
        alert('当前浏览器 Not support websocket')
    }
//连接发生错误的回调方法
    websocket.onerror = function() {
        alert("WebSocket连接发生错误")
        setMessageInnerHTML("WebSocket连接发生错误");
    };

//连接成功建立的回调方法
    websocket.onopen = function() {
        setMessageInnerHTML("WebSocket连接成功");
    }
//接收到消息的回调方法
    websocket.onmessage = function(event) {
        alert("这是后台推送的消息："+event.data);
        setMessageInnerHTML(event.data);
    }
//连接关闭的回调方法
    websocket.onclose = function() {
        alert("WebSocket连接关闭");
    }
//监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function() {
        closeWebSocket();
    }
//关闭WebSocket连接
    function closeWebSocket() {
        websocket.close();
    }
//将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('resp').innerHTML = "";
        document.getElementById('resp').innerHTML = innerHTML;
    }
}
